Apparatus have heretofore been made for supporting and holding large workpieces having a contoured holding surface. In general, these apparatus include an array of vacuum cups mounted on spindles for adjustment relative to a base for holding a workpiece on the upper ends of the spindles. In U.S. Pat. No. 4,088,312, vacuum cups are mounted on parallel spindles with springs for urging the spindles and vacuum cups to individual raised positions and pneumatically actuated clamps for clamping the spindles in an adjusted position. In U.S. Pat. No. 4,684,113, a screw actuator is provided for adjusting the height of each spindle and a pneumatically actuated clamping means for locking the spindles in an adjusted position. In the above patents, the holding force generated by vacuum cups is generally parallel to the axis of the spindles and the vacuum cups are not adequate to effectively resist forces having a substantial component in a direction transverse to the spindles.
U.S. Pat. No. 4,527,783 discloses a plurality of vacuum cups mounted on a flexible lattice type spring metal framework that is adjustable relative to the base by linear actuators to form a contoured support plane. U.S. Pat. No. 4,491,306 discloses a work holding apparatus in which each work holder has a cup shaped vacuum chamber which is swivelly supported on an upper end of a spindle with a work engaging pin inside the open end of the cup shaped vacuum chamber.